Multiple micrometer



Sept. l2, 1944.

E. L. KELLAN 2,357,898 V MULTIPLEY MICROMETER Filed Dec. 31, 1942 Patented Sept. 12, 1944 MULTIPLE MICROMETER Edward L. Kellan, Chicago, Ill.

Application December 31, 1942, Serial No. 470,767

4 Claims.

The present invention relates to instruments for measuring dimensions of objects and has for its purpose to produce a simple and novel precision instrument for making a considerable variety of measurements such as inside and outside dimensions and depths over a wide range. and diameters of internally and externally threaded objects at the bottoms of the valleys between threads.

The various features of novelty whereby my invention is characterized will hereinafter be pointed out with particularity in the claims; but, for a full understanding of my invention and of its objects and advantages, reference may be had to the following detailed description taken in connection with the accompanying drawing, wherein:

Figure 1 is a side view of an instrument embodying my invention in one of its forms; Fig. 2 is an edge view of the instrument, looking at the latter from the left of Fig. 1; Fig. 3 is a section on line 3-3 of Fig. 1; Fig. 4 is a longitudinal section through the micrometer head, showing also a small fragment of the body of the instrument adjacent to the head; Fig. 5 is a side View of two bars more or less like those in Fig. l, close together instead of being spread apart as in Fig. 1; Fig. 6 is a side View of a bar adapted to be substituted for one of those shown in Fig. 1; and Fig. 7 is a detail illustrating a modified way of locking the movable bar of the two parallel bars to the guide rod.

Referring to the drawing, I and 2 represent two bars of any desired length. Screwed into the bar I, to which I shall refer as the upper bar, is a sturdy sleeve 3 calibrated in the manner usual in the case of corresponding elements of micrometers. Surrounding the member 3 is a deep cap 4. Extending up through the bar I and through and in screw threaded relation to the sleeve 3, is a round stem 5. The upper end of this tem is secured to the transverse or bottom wall 6 of the member 4, in any suitable manner. In the arrangement shown, the stem has at its extreme upper end a short section I of reduced diameter. Nuts 8 and 9 on this stem, engaging with the under and outer faces of the wall 6, respectively, hold the member 4 rigidly on the stem. In the arrangement illustrated. the screw threads on the sleeve 3 and on the parts I are right hand threads whereas those on the body of the stem 5 are left hand threads. With this arrangement the cap member 4 turns in the same direction as would the corresponding member of the ordinary micrometer, so that one used to handling an ordinary micrometer may turn the cap in the manner with which he is familiar. However, this disposition of the threads is not essential.

It will be seen that when the cap d is turned, the stem 5 is shifted lengthwise up or down, depending upon the direction in which the cap turns. 'Ihe stem 5 extends freely through the bar 2, so that this bar may slide up and down relatively to the stem. In order to prevent the bar 2 from swinging about the axis 0f the stem relatively to the bar I, I provide a guide rod I0 which is screwed into the under side of the bar I so as to lie near and parallel to the stem. This rod extends through and is a sliding fit in the bar 2. The bar 2 may be fastened to the guide rod I0 at any point on the latter, by means of a set screw I I or otherwise.

The stern 5 is provided with grooves I2 extending completely around the same at intervals, preferably exactly one inch between centers where measurements are to be made in inches or fractions thereof. Lying within a depressed portion in the top of the bar 2 is a short dog I4 shown as being held ln place by a screw I5 that parallels the stem. The thickness of this dog is equal to the width of the grooves I2 so that when the bar is brought into such a position that the dog registers with one of the grooves, the dog may be swung into that groove and thus lock the bar to the stem against relative movements lengthwise of the stem. The upper face of the dog I4 is in the same plane as the unmutilated parts of the upper face of the bar. Therefore, when the dog is engaged with the uppermost groove, for example, the distance between the working faces of the bars is exactly one inch. The screw thread y on the stem may terminate at the uppermost groove because the micrometer head need only have the capacity to shift the stem lengthwise through a distance of one inch. If measurements greater than one inch are to be made, the additional inches are obtained by shifting the bar 2 along the stem until its dog registers with the groove corresponding to the number of full inches; the fractions being then obtained through the turning of the cap of the micrometer head.

The stem may be of any desired length. I prefer that it be only a few inches long to keep its length reasonably small except when large diameters are to be measured. Additional stem sections may be provided for accurately increasing the length of the stem indefinitely. In the arrangement shown, the stem proper extends only three inches below the bar I. Screwed into the lower end of the same is a second stem section IB which is two inches long. This added section is shown as having a pointed end portion II screwed into the lower end of the same; a pointed end being advisable when the instrument is being used as an ordinary depth gauge. The section I6 and its detachable end element I'I are shown only by way of illustration, since there is no limit to the variety of lengths and additional sections that may be employed. In order to facilitate the assembling together and the dissembling of stern sections, the main stem may be provided with a little hole I8 through the same, and each Hummm detachable section may be provided with a similar hole. Pins may be inserted in these holes to produce relative turning movements between sections that are coupled together or to be coupled together, to turn them relatively to each other.

Corresponding ends of the bars I and 2 are shown as having pointed fingers I9 and 20 projecting therefrom in the lengthwise direction. Each of these fingers has one long straight edge 2| lying in the plane of the working face of its bar. The parts are so proportioned that when the bars are in contact with each other, as are the two bars in Fig. 5, these fingers have passed each other so as to bring their straight edges into the same plane. With these fingers internal diameters or other similar transverse dimensions may be measured, the smallest measurable diameter being in the vicinity of one-thirty second of an inch, and the largest depending only on the length of the stem that can be obtained. External dimensions may conveniently be measured by the opposite ends of the bars. Since the iingers I9 and 20 are preferably secured to the bars, or at least, in fixed positions when they are detachable as illustrated, I provide means at the other ends of the bars for properly adjusting them to insure that both internal and external dimensions may be accurately measured. In the arrangement shown, the bar I is provided with a screw threaded hardened pin 22 extending through the same near the end opposite that at which the ilnger I9 is located. The lower end of the pin has a flat, true surface which, when the two bars are brought in contact with each other, must touch the underlying at face on the bar 2. In order properly to adjust the bars, they are placed together, with the dog in the uppermost groove. If the working edges of the two fingers I9 and 20 are not in exactly the same plane, the ngers must be ground or otherwise finished to bring them both into the plane of contact between the bars. The pin 22 is then adjusted until it just touches the bar 2, and it is secured ln this adjusted position by a locking screw 24.

Means are also provided to measure the diameter of an externally threaded member at the bottoms of the valleys. This may conveniently consist of two pointed pins 25 and 26 screwed through the bars I and 2, respectively, parallel to the stem and having their pointed ends directed toward each other. In order initially to adjust this part of the instrument, the pins 25 and 26 are turned while the bars are in contact with each other, until the points of the pins just touch. The pins are then fastened in these adjusted positions by holding screws 21.

In the particular construction illustrated, only external screw threaded members of small diameter can be measured, this being due to the proportions which the parts have. Obviously, the only limiting factor with respect to the size of the member which can be measured, is the distance of the pins 25 and 26 from the stem, since the radius of the member to be measured cannot be greater than this distance.

It should be noted that the underside of that end of the bar containing the pins 22 and 25 must be cut back so as to allow these pins to project. Likewise, the point of the pin 2B is preferably placed along the depression in the top of the bar 2 in which the dog I4 lies.

For the purpose of measuring inside diameters or other transverse dimensions, or diameters of externally screw threaded members at the botmeasurements is being made.

toms of the valleys in the latter, bars 29 such as illustrated in Fig.- 6 may be employed. The iinger 30 in this bar corresponds to the nger I3 in Fig. l. However, instead of having a long straight edge for contact with the work, the finger is provided with an upturned point 3|, the tip of which lies in the plane of the under face of the bar. When a cooperating bar underlying the bar 29 is engaged with the latter, the tips of both lingers will lie in the plane of contact between the bars. When the bars are separated as in Fig. 1, the tips of the little points or projections 3| lie in the same relative positions to each other as do the long straight edges 2|, and thus may be engaged with the inner surface of any object whose internal diameter or other transverse dimension is to be measured. It will also be seen that if this surface is screw threaded, the points may enter the valleys between the threads and thus measure the internal diameter at the bottoms of such valleys. The pointed end of the bar 29 may be provided with a protective shield 32 that overlies the point 3| and guards against contact of the latter with the hand of the user when, for example, one of the other types of The guard or shield 32 is shown as being hinged to the bar 29 at 34 so that it may be swung back and lie on top of the bar when the finger 30 is needed to make a measurement.

It should be noted that while Fig. 5 illustrates the same fingers as those appearing in Fig. 1, the bars 35 and 36 are illustrated as taking the simplest form for making both inside and outside measurements; the object whose external dimension is to be obtained being simply placed between the right hand ends of the bars.

The guide rod I0 may also be provided with extensions which may be screwed into the lower end of the same as are the extensions for the stem 5. In the arrangement shown, there is a special extension 31 in the form of a scratch awl. The guide rod is provided with a hole 38 similar to the holes I8 in the stem to receive a pin for turning it or for holding it against turning while screwing it into or out of position or attaching or detaching an extension.

If desired, the bar 2 may be locked to the stem in the manner shown in Fig. 7, wherein a screw I3 extends through one side of the bar and into the selected groove in the stem. This expedient is particularly useful with such bars as those in Fig. 5.

The manner of using the instrument perhaps needs but little further explanation. If an inside diameter of less than an inch is to be measured, the screw II is loosened while the bar 2 remains locked to the stem in the position shown in Fig. l. The cap on the micrometer head is then turned until the ngers I9 and 20 are near enough to each other to enable them to enter into the space to be measured. The cap is then turned in the opposite direction until the working edges of the ngers make contact with the inner surface of the object and the size of the dimension is given by the micrometer reading. If the dimension be one that is greater than one inch, the bar 2 is dropped down until the dog registers with the groove in the stem that corresponds to the number of inches which is one greater than the number of full inches which such dimension measures. After the dog has been swung into the selected groove, the measurement is taken in just the same way as before. If the dimension to be measured is longer than the stern, an exi3. UiUIVIt l inw.,

...titoli/ums. Lxamlllci tension of the necessary length is added and the bar 2 is lowered to the proper groove in the extension.

In order to measure an outside dimension, the

which passes freely through said bar and extends beyond the latter a distance much greater than the distance that can be indicated on said head, a second bar through which said stem extends steps are the same as those described in connec- 5 and on which it is slidable, means to hold said tion with making inside measurements, except bars parallel to each other in all relative posithat the bars are always first spread apart far tions of the same, and means to lock the second enough to permit the object to be measured to bar to the stem at any one of a plurality of points be received between the lower end of the pin 22 distributed along the stem to hold the bar against and the underlying end of the bar 2; the cap on 10 movement along the stem while allowing the latthe micrometer head being then operated to draw ter to rotate freely in the second bar. the bars together until both touch the object. 2. An instrument of the character described, The measuring of an externally threaded memcomprising a bar, a micrometer head secured to ber is done in the same way in the case of any and projecting at right angles from the bar, said other external dimension, except that the points l5 head including an axial screw-threaded stem of the pins 25 and 2B enter and bottom in the which passes freely through said bar and extends valleys of the threads. As heretofore stated, only beyond the latter a distance much greater than screw threaded members of small diameter can the distance that can be indicated on said head, be measured in this way by the particular instrua second bar through which said stem extends ment which is shown by way of illustration. 20 and on which it is slidable, means to hold said By substituting the bar 29, and a complemenbars parallel to each other in all relative positary bar of the same kind, for the bars I and 2, tions of the same, said stem having a plurality of internal diameters of both plain and internally circumferential grooves distributed lengthwise of screw threaded objects may be measured by the the sarre in spaced rela-tion to each other and fingers whose points 3| perform the functions 23 to the first bar, means on the second bar to be of the working edges 2| of the fingers I9 and 20 entered into any one of said grooves and thereby and of the pointed ends of the pins 25 and 26. lock the second bar to the stern. and iingerS DTO- Actually, of course, it is unnecessary to remove jecting lengthwise and also laterally from correthe bars I and 2, for the fingers of the type shown spending ends of the bars in such positions that in Fig. 6 are interchangeable with those in Fig. 1. 30 the ingers overlap each other when the bars are To this end all of the fingers are secured to their in contact with each other. respective bars by little screws so that by ac- 3. An instrument of the character described, curately forming the fingers, finger 30, for examcomprising a bar, a micrometer head secured to ple, may be substituted for finger I9, and a finger and projecting at right angles from the bar, said complementary to finger 3|] (not shown) for the 35 head including an axial screw-threaded stem finger 20. which passes freely through said bar and extends In using the instrument as a depth gauge, the beyond the latter a distance much greater than stem, provided with a pointed end, as shown, may the distance that can be indicated on said head, be let down into the space in an object whose a, second bar through which said stern extends depth is to be measured, until it touches bottom. and @n which it is sutiable, means to hold said Then the bar 2 may be lowered until it rests on bars parallel to each other in all relative posithe object and be locked to the guide rod. The tions of the same, said stem having a plurality stem being graduated, as shown as 40, a direct of circumferential grooves distributed lengthwise reading upon lifting the instrument out of the of the Sarre in such positions that the first groove object gives the information desired. If a miis spaced apart from the first bar and adjacent crometer reading be desired. the bar 2 may be grooves are from center to centeradistance equal locked at the first groove in the stem that is above to the range of readings for which the micromthe top of the object while the lower end of the eter head is adapted. graduations along said stem, stern is still out of contact with the iioor of the and a deg on the second bar to be'entered into cavity to be measured,but less than an inch above any one of said grooves and thereby lock the the same. Then, after unlocking the bar from second bar against movement along the stem the stem, the cap on the micrometer head is while permitting the latter to rotate. turned until the stem has been lowered to the 4. An instrument of the character described, floor of a cavity. The reading of the micrometer, comprising a bar, a micrometer head secured to added to the known length of stem that originally 56 and projecting at right angles from the bar, said extended down into the cavity, namely the even head including an internally screw-threaded number of inches represented by the groove in sleeve fixed to and projecting beyond the bar at which the dog I4 lies, less one half inch or whatone side of the latter and a stem provided with ever thickness the bar 2 may have, gives the depth a cap fixed thereto and fitting over the stem, of the cavity. Of course the micrometer reading 00 said stem being in screw-threaded relation to must be zero at the start of making this last type the sleeve and extending freely through the bar of measurement. for a distance beyond the opposite side of the While I have illustrated and described with latter much greater than the distance that can particularity only a single preferred form of my be indicated on said head, a second bar through invention including a few modifications, I do not which said stem extends and on which it is sliddesire to be limited to the exact structural details able from a position in which it contacts the first thus illustrated and described; but intend to cover bar, a guide rod fixed to the first bar and coall forms and arrangements which come within operating with the stem to hold the bars parallel the definitions of my invention constituting the with each other in all relative positions of the appended claims. same, and means to lock the second bar t0 the I claim: stem at any one of a plurality of points distrib- 1. An instrument of the character described, uted along the stem and at the same time Permit comprising a bar, a micrometer head secured to relative rotary movements. and projecting at right angles from the bar, said head including an axial screw-threaded Stem EDWARD L- Imm-'AN' 

